Methods are known for the preparation of saturated ketones by the catalytic transfer of a hydrogn atom from a primary or secondary alcohol molecle or from a glycol to a molecule of an .alpha.-, .beta.-unsaturated ketone.
The reaction results more or less shifted in the desired direction depending on the catalyst used, on the parametric conditions, etc. In general, it is best operated by using isopropanol as the alcohol donor, due to facility of separating the acetone deriving from de-hydrogenation. Nevertheless, the catalytic activity turns out to be rather low and the regio-selectivity insufficient.
Therefore, there were studied different catalytic systems that will allow to operate in a homogeneous phase. They are essentially based on the use of complexes of transition metal of Group VIII, amongst which the most studied are those derived from iridium and from ruthenium.
Thus, there have been suggested complex catalysts of the formula:
IrHCl.sub.2, (DMSO).sub.3 wherein DMSO=dimethylsulphoxide: RuCl.sub.2 =(C.sub.6 H.sub.5).sub.3, operating in an acid (HCl), neutral or alkaline or definitely alkaline medium respectively.
Generally, the primary alcohols like isopropanol are used as alcohol donors. With ruthenium catalyst benzyl alcohol is a preferred alcohol donor.
In general, however, the activity or the stereoselectivity obtained in the described substrate is not high. This is an undesirable drawback since the reaction, as previously explained, is selectively directed to yield fine chemical compounds for which the steric aspect is of the utmost importance.
Furthermore the catalyst described hereinabove provide in general unsatisfactory reaction rates no doubt lower (even of the order of 100 times), and for the iridium catalysts even 10.sup.4 times, than the ones achievable by the use of the catalysts according to this invention, which later, therefore, ensure aspects of a more pronounced industrial applicativity.